Stability of Detonation Nanodiamond Colloid with Respect to Inorganic Electrolytes and Anionic Surfactants and Solvation of the Particles Surface in DMSO–H2O Organo-Hydrosols

Abstract

In this article, the stability of sols of detonated nanodiamonds, DND, with positively charged colloidal particles, is studied in different salt solutions in water–dimethyl sulfoxide (DMSO) binary systems containing 95 vol.% organic solvent. Additionally, several CCC values are determined in 95 vol.% acetonitrile for comparison. The critical coagulation concentrations (CCC) are determined using the dynamic light scattering technique and the Fuchs function. As coagulators, NaCl, NaBr, NaNO3, NaClO4, Nan-C8H17SO3, and Nan-C12H25OSO3 are used. Comparison of the CCC values in DMSO–H2O and CH3CN–H2O with those obtained in water allows us to make some conclusions. The variations of these values in different solvents are explained in terms of good and poor interfacial solvation of colloidal particles, “structural” contribution to the interparticle interaction energy, lyotropic series for anions, and more or less pronounced adsorption of surfactants. The study of the stability of DND hydrosol in solutions of anionic surfactants with different hydrocarbon tail length demonstrated the crucial role of adsorption in the coagulation process.

Stability of Aqueous Suspensions of COOH-Decorated Carbon Nanotubes to Organic Solvents, Esterification, and Decarboxylation

“…Even in the case of the colloids of detonated nanodiamond with positively charged particles, the CCC for NaCl in 95 vol % DMSO is 5.9 times higher than in 80 vol % CH 3 CN, despite the sp 3 -hybridization of the carbon atom in this case . For NaClO 4 , the difference is 10-fold …”

“…19 For NaClO 4 , the difference is 10-fold. 22 Hence, it can be expected that in water, like in solvents with high Gutmann's Donor Numbers, DMF and DMSO, specific stabilizing solvation factors are present, which can be considered as a kind of non-DLVO (Derjaguin, Landau, Verwey, Overbeek) contribution. By considering only aqueous systems and only the electrostatic repulsion and molecular attraction, one can miss important factors that regulate colloidal stability in the presence of electrolytes.…”

Colloid Chemistry of Fullerene Solutions: Aggregation and Coagulation

“…In contrast, diluting the initial suspension with DMSO and DMF does not lead to a significant change in the CCC [268]. For organohydrosols of detonated nanodiamond, DND, with positive particle charge [269], the CCC values of most inorganic salts are higher than in water, if DMSO is the organic component, whereas in the mixtures of water with acetonitrile a pronounced drop of the CCC is observed. Here, the carbon atoms are in a state of sp 3 hybridization, but the strong solvation of DMSO particles is obviously due to the interaction of this cationophilic solvent with cationic centers on the DND surface.…”